A breeding program has been developed since 1989 (done by Dr. A. Trigui) for improving the oil content and the quality of the most important olive variety cultivated in Tunisia ‘Chemlali’. Studies realized on these new obtained descendants, showed that some progenies presented higher oil percentage and a better chemical composition, comparing with the original cultivar ‘Chemlali’. However, there is a little understanding about phenotypic diversity distribution according to their genetic origins. The present work was carried out in order to study the morphological variability noted on thirty ‘Chemlali Sfax’ seedlings issued from self, free and cross pollination with ‘Coratina’. Seventeen morphometric parameters were used according to the different parts of the olive tree (tree, leaf, fruit and endocarp). For identification the patterns of morphological variation within the progenies, Principal Component Analysis (PCA) was used and cluster analysis was performed to decide the ultimate numbers of clusters by which the accessions could be assessed. Quantitative characters revealed significant differences between seedlings within all crossbreeding (P≤0.001-test Duncan). Wide ranges of variation were noted. The highest CV was recorded for fruit weight, which was equal to 89.4%, 72.3% and 39.2%, respectively for free, self and cross pollination. Results revealed that the first three Principal Components (PCs) explained 75.5% of the total variation observed in-situ. Fruit, endocarp and leaf size were strongly associated with the first principal component. Fruit and endocarp shape showed the highest contribution to inertia on the second one. Trunk circumference and leaf shape were strongly related to the last one. Projection of seedlings in the plane determined by the first two principal components, showed that seedling issued from ‘Chemlali’ x ‘Coratina’ were grouped and showed the smallest fruits and endocarps, the biggest leaves and vigorous trees. While ‘Chemlali’ free and self pollination seedlings were characterized by medium fruit and endocarp weight, medium leaf size and medium tree vigor. However, cluster analysis revealed four groups for the studied descendants related to the great discriminated effect which was fruit size. The results of morphological evaluation confirmed the usefulness of phenotypic markers for olive genetic resources but the number of descriptors used in this study could be reduced.
